Unidirectional Dual-Band Stacked Patch Antenna With Independent Frequency Reconfiguration

Abstract

A novel dual-band frequency-reconfigurable stacked patch antenna is presented. The antenna comprises two stacked square patches. Each patch is divided into two rectangular portions by a gap, and a pair of varactor diodes is introduced to bridge the gap. By changing the reverse bias voltages across the two pairs of varactor diodes, the antenna can operate at dual frequency bands with independent frequency tuning. A fully functional prototype is fabricated and characterized. It exhibits a continuously dual frequency-tunable characteristic, from 1.68 to 1.93 GHz for the low band and from 2.11 to 2.51 GHz for the high band. Well-controlled unidirectional radiation patterns are achieved at all operating frequencies. To the best knowledge of the authors, this is the first dual-band reconfigurable patch antenna with an independent frequency tuning ability. The dual-band frequency selective feature makes the antenna potentially suitable for future wireless communication systems, such as cognitive radio.